1. Field of the Invention
The invention relates to a medical device which illuminates in accordance with moving of a field of view, and obtains image information of an object to observe.
2. Description of the Related Art
At a tip end of a body of an endoscope as a medical devicemedical device, there are provided an imaging apparatus which obtains a video image as image information by imaging an object to observe, and an illumination unit which illuminates the object for imaging. The imaging apparatus does not need movement of the field of view to image and employs an imaging optical system with a fixed focus up to the present. The field of view is therefore fixed. A common illumination unit is provided with an illumination window at a tip end thereof, and guides illumination light with a light guide fiber from an external light source, in order that an area slightly greater than a field of view is illuminated at a desired uniform luminous intensity.
In a rigid endoscope, an insertion unit is hard, and an imaging apparatus (objective lens) provided at a tip end thereof is integrated with the insertion unit. Therefore, the insertion unit needs to be moved in order to catch a portion to observe within a field of view.
In contrast, as a technology to move a field of view without moving an insertion unit, for example, Jap. Pat. Appln. KOKAI Publication No. 52-71888 proposes an endoscope of a field-of-view transformable type in which a pivotal field-of-view transformer is provided at a tip end of an image guide. In brief, a mirror is provided to be pivotal. The field-of-view transformer is connected to a wire, and the field of view is observed arbitrarily by pushing and pulling the wire.
Jpn. Pat. Appln. KOKAI Publication. No. 52-71888 proposes a conceptual embodiment. When applied to an endoscope in which a solid-state image sensing device, such as a CCD, is used as an imaging apparatus, a movement mechanism which makes the imaging apparatus movable together with an illumination unit has a complex configuration, and a tip end is not easy to make smaller.
Accordingly, even in a mechanism which makes an imaging apparatus movable, an illumination window for emitting illumination light is fixed to a tip end. The mechanism can easily have a configuration for illumination which covers a whole range of a field of view of the movable imaging apparatus. In a proposed endoscope which makes an imaging apparatus movable, illumination is constantly achieved so as to cover a whole field of view within a movable range of the imaging apparatus from an illumination window.